Locomotive draft appliance



SePf- 29, 1936 A. GlEsL-GlEsLlNel-:N

LOCOMOTIVE DRAFT APPLIANCE Filed Feb. 1s, 1932 Sept. 29, 1936. A. GIESL-GlEsLiNGEN LOCOMOTIVE DRAFT APPLIANCE Filed Feb. l5, 1932 2 Sheets-Sheet 2 Patented Sept. 29, 1 936 uNlTED-js'rATEs PATENT oFFics LOCOMOTIVE DRAFT APPLIANCE Adolf Giesl-Gieslingen, New York, N. Y.

Application February 13. 1932, Serial No. 592,710

8 Claims. (Cl. 23o-96) My present invention relates to draft appliances for steam locomotives, in which the draft required for the fire is created by suction obtained from the exhaust steam.

In such draft appliances, a steam jet, mainly the exhaust from the locomotive driving engine, is used to create a .partial vacuum in the socalled smokebox oi the boiler, thereby pumping the air and products oi combustion through the boiler and discharging them through the smokestack into the atmosphere. Locomotive boilers require for their operation a tar stronger draft than any other commercially used steam generator. When working at full capacity, the combustion gases pass through the boiler tubes at a speed oi lo@ feet per second and more, and through the smokestack at speeds often exceed-y lng 600 feet per second. Therefore, large amounts of energy are required to produce X such draft, representing substantial percentages (often 30% and more) oi the totalglocomotive performance, that would otherwise be available in form of useful work at the drawbar. The problem oi producing locomotive boiler draft in an economical manner has always been in thel foreground and consequently, inventive ingenuity has been attracted thereto to a special degree. creating a, great variety of devices within a century oi' development. However, the subject has so far evaded o. satisfactory solution. It hasnot been possible to devise general rules for the design of such draft appliances and the subject continues to be vital to an even higher degree than before, since modern locomotives are working harder and are suffering greater losses from back pressure caused by ineihcient draft appliances, and are wearing out too quickly some of the devicesthat have been developed to increase efeiency.

lit is the purpose of my invention to create draft appliances of new and greatly improved general characteristics and utility, wherefore I primarily seek the following objects:

l. Maximum efficiency of action,

' 2. Stronger draft when the locomotive is starting or working heavily at slow speed,

3. Maximum lateral expansion or divergence of the exhaust steam jet, effected with a minimum or no additional expenditure of energy.

4. Minimum wear of the device by minimizing the grinding action of cinders passing through.

Object l may be 'analyzed 'and divided into the following requirements, which are being iullled by my invention:

(a) Mixing the exhaust steam with the combustion gases after a relatively high speed has been imparted to said gases, thereby minimizing energy losses due to the inavoidable shock occurring when gas and steam come in contact with each other,

(b) Affording thorough mixture of gas and steam by forcing the former into the steam current and providing for sufficient time for the` currents to thereafter adequately equalize.

(c) Providing a divergent path for gas and steam during the major part of the processes of mixture and of equalization between gas and steam currents,

(d) Dividing the processes of entrainment and consequent mixture of gas and steam into two or more sections by the use of intermediate nozzles, thereby further decreasing energy losses and providing suction at different points along the length of the device, which latter feature usually has a beneficial eifect upon the steam boiler. o

Object 2 is designed to avoid the usual tendency of the boiler pressure to fall oil?` when a locomotive with the presently known draft appliances is starting a heavy train.

`Object 3 is of vital importance for the following well-known reasons, discussed in more detail in my co-pending application Serial No. 441,894 now Patent No. 1,869,991, Aug. 2, 1932: To function proper1ya locomotive smokestack must be completely lled by the exhaust steam jet, at 30 least near the outlet or top. Therefore, the crosssectional area of such smokestack near the top must never be larger than that of said exhaust jet. Due to the natural divergence of a steam jet escaping from an orifice, almost any desired area may be .filled by the jet at the proper distance from said orifice. but locomotives have reached proportions which, as a rule, make it impossible to provide sufficiently wide smokestacks since there is not enough room for the required length of the draft appliance. rllltierefore, it is quite general practice to employ some means of spreading the exhaust steam which involve considerable lossesin energy, while my invention promotes lateral expansion of the steam jet without any harsh and harmful coercive spreading.

Object 4 requires no further discussion since it is well known that cinders entrained by the steam jet have a highly abrasive action. Therefore, I design and locate the various parts of my invention in such a way as to largely avoid direct contact with the steam jet.

To these ends, I provide the draft appliance with one or more intermediate nozzles diverging 55 toward their outlets, and combine various other'- features as hereinafter set forth. 4

There is great confusion among those skilled in the art as to the characteristics promoting optimal function of a draft appliance. After nearly a decade of wide study, I established rules embracing most of the above enumerated requirements as well as some further features which will appear later in this specification, and I succeeded in discovering simple means by which my findings can most effectively be put into practice. In the state of the art prior to my invention, however, I know of no device that fulfills any of the requirements established by me without antagonizing part of said requirements to the detriment of efficiency and utility.

In the accompanying drawings, Fig. l is a 1ongitudinal section through a conventional construction of locomotive smokebox wherein one embodiment of my invention is shown. Fig. 2 is a transverse section through the same smokebox, corresponding to Fig. 1. 1

Figures 3 and 4 are diagrammatical sketches of Y preferred forms of my invention, in longitudinal section.

Fig. 5 is a diagrammatical sketch of a modified exhaust nozzle, and Fig. 6 a sketch of a modified intermediate nozzle, both shown in longitudinal section.

Fig. 'lis a diagrammatical sketch of a preferred form of my invention in which I use an intermediate nozzle adapted to split the exhaust steam jet. Fig. 8 is a section through the intermediate nozzle shown in Fig. 7 along the line tl-t, Fig. 9 is a top view of said intermediate nozzle, and Fig. '10 a top view of a modified form of such intermediate nozzle.

Figures 11, l2, and 13 illustrate an example of an incorporation of my invention in a draft appliance of other than circular (oblong) cross section, Fig. 11 being a diagrammatical longitudinal section, Fig. 12 a like transverse section at a right angle thereto, and Fig. 13 a cross section through the intermediate nozzle along the line |3-|3 in Fig. il.

Referring to Figures l and 2: A conventional locomotive boiler is shown merely as an illustration, without intent to limit the application of my invention to any particular construction of boiler. The cylindrical barrel i contains the re tubes 2 through which the combustion gases pass into the smokebox 3 as indicated by the arrows t, 5. A smokestack 6 is mounted on top of the smokebox. 'The exhaust nozzle 'I is, as usual, mounted on the standpipe 8 into which the exhaust steam enters from below, upon which said steam Vis discharged through the stack 6, entraining the surrounding combustion gases., All the foregoing features are well known.

ABefore entering the stack, the exhaust steam passes through the intermediate nozzle 9 which may for example be supported on the standpipe by means of arms I0 and the ange H. No nettings nor baille plates for arresting sparks are shown and the arrangement may thus be used for an oil-burning locomotive, but of course, any type of spark arrester may be incorporated if desired.

The term "intermediate nozzle as I understand it, in order to be distinguished from devices of similar appearance but distinctly different use that are sometimes connected with spark arresters and the like, may be dened as follows,A

with reference to Figures 1 and 2:

In the now most common form of draft ap'- pliance, the exhaust steam is discharged from the nozzle 'H directly into the stack 6, and is in free contact with the surrounding combustion gases while on its way from said nozzle to said stack. The stack is then usually longer, about following the dotted lines i2. The exhaust steam jet, owing to its natural tendency, expands laterally, forming a cone I3. There is not much opportunity for the exhaust steam and the combustion gases to mix thoroughly on the short way between the exhaust nozzle 'l and the stack inlet l2: Steam and gas travel more or less parallel to each other and the stack fullls also the function of uniformly mixing them which is essential for satisfactory draft-producing action.

Through the introduction of the intermediate nozzle 9, interposed between the exhaust nozzle i and the stack t, the processes of entraining the gases and of mixing them with the steam are divided into two parts. Likewise, the interposltion of a number n of such intermediate nozzles would divide said processes into n plus 1 parts. An intermediate nozzle is similarly situated relative to the nozzle preceding it in the course of the exhaust steam now, as the commonly used simple smokestack i2 is situated relative to its correponding exhaust nozzle l and, in combination with said preceding nozzle, acts analcgously to such commonly used smokestack with its corresponding exhaust nozzle. Therefore, an intermediate nozzle may be defined as a partial smokestack, and has an analogous function, namely to promote adequate mixture of the exhaust steam with a part of the combustion gases and to discharge said mixture in form of an orderly stream wholly into the stack or the next intermediate nozzle, where it mixes with an additional amount of combustion gas. It will also be appreciated, and I have proved theoretically, that the device herein defined as intermediate nozzle must be of proper proportions in order to fulfill the above functions: Its smallest cross-sectional area must be larger than the outlet area of the nozzle irnmediately preceding it, while its outlet area must be smaller than. the minimum cross-sectional area of the nozzle or stack immediately following it. Its axial length should be at least equal to its minimum diameter since it cannot otherwise afford adequate mixture of gas and steam. lIhe gas passage formed between the inlet of an intermediate nozzle and the outlet of the nozzle preceding it, as well as that formed between the outlet of said intermediate nozzle and the inlet of the nozzle or stack following it must be of substantial size and at least equal to the minimum cross-sectional area of the stack divided by the number of gas intakes n plus l as above dened. Y If these characteristics are not present, the devices referred to cannot act as intermediate nozzles in the proper sense of the word and cannot substantially improve but may even hinder the draft-producing action.

Hitherto, intermediate nozzles, more commonly under the name of draft pipes, lift pipes or petticoat pipes, have often been used for the purpose of dividing the gas intake of the draft appliance, thereby establishing suction at different heights relative to the boiler tube sheet and promoting more uniform draft action on all boiler tubes than obtainable with a single gas intake. With this object in mind, intermediate nozzles have been made with a cylindrical body fiaring out somewhat at the bottom in order to safely catch the incoming steam jet. Sometimes it was found that wider exhaust nozzles could be used in connection with such intermediate 7 nozzles, indicating also a saving in exhaust energy; this was particularly-true in connection with smokestacks of relatively large cross-sectional area, common on small locomotives. However, enlarge locomotives where relatively narrow stacks are being used for several reasons. cylindrical intermediate nozzles not only showed but little beneilt, but were often detrimental to blast efficiency. Y

Recognizing the need for improvement, frequent attempts have beenmade to use intermediate-nozzles'of other than cylindrical shape.

' The leading consideration has been to restrict the flow within the intermediate nozzle near its outlet in order to increase the speed of said now as it'escapes from said nozzle, expecting that this may promote a more powerful draft. As a rule, these attempts have-failed, but the reason therefor has hitherto not been recognized. I have been able to prove that occasional success was attributable to other causes than said principle of restricting the ilow. l

On the contrary, I succeeded in establishing that an` intermediate nozzle should diverge toward its outlet, that is, should provide a gradually increasingcross-sectional area for the iiow through it for a substantial part of its length in order to increase the eiliciency of a locomotive draft appliance to the theoretical maximum. I have further discovered that this finding can be utilized to construct greatly improved draft appliances since the several objects listed earlier in this specification may be simultaneously effected by so designing and locating such divergent intermediate nozzles in connection with exhaust nozzle and smokestack as will now be described.

Fig. 3 shows the simplest form of my invention. The intermediate nozzle 9 diverges in the direction of the iiow through it and is iitted with a considerably daring intake l5. I prefer to use with said intermediate nozzle, a stack 6 of substantially similar longitudinal shape having likewise a diverging outlet and a wldelyilaring intake i6, and to form said stack with a short cylindrical portion i1 between the intake and the diverging portion, since I discovered that it is beneilcial to let as much as possible of the mixture between gas and steam take place within the narrowest part oi the stack.` This latter principle also applies to the intermediate nozzle, and a modification incorporating it is illustrated in Fig. 6, showing e. cylindrical throat il in the nozzle Ba, but it can be seen that such a throat in the intermediate nozzle will tend to reduce the lateral expansion of the steam jet and will therefore requirea greater length of the draft appliance which is not always available. The cylindrical portion il of the stack, 'although not having much eiiect upon the length required for the device, may also be dispensed with if the draft appliance is to ce especially short.

The exhaust nozzle 1 as shown is ci the wellknown slightly converging form, having a cylindrical portion at its outlet. However, I sometimes preier to make the exhaust nozzle slightly divergent as shown at I9 in Fig. 5: this' will give the steam jet the proper conical shape before escaping from the exhaust tip, resulting in the smoothest how. Diverging exhaust tips already been used, but for other purposes and without success. Sharp distinction must be made between the function of an exhaust nozzle and that of an intermediate nozzle: the latter serves to mix gas and steam, and a divergent outlet greatly increases its suction power and saves have Y energy in addition to other functions; an exhaust nozzle, however, primarily serves to let the steam expand properly, and since in a good draft appliance the average exhaust pressure should be well below the so-called critical pressure," of about 12 lbs. per square inch, the exhaust steam passage should converge toward the nozzle tip `from a purely thermodynamic standpoint.- A

slight divergence at the outlet will however cause no thermodynamic loss.

Returning to Fig. 3: The exhaust tip having the diameter B may be connected with the top of the smokesta'ck having the diameter C by a hypotheticai cone Iii, which serves as a basis for proportioning my invention. Length A of said cone should preferably be more than four and a half or ilve times the diilerence between its maximum and minimum diameter, C minus B. 'Ihe smokestack should be made as wide at the top as consistent with service requirements well known to those skilled in the art, andthe width of the exhaust nozzle may be chosen from experience. In most cases, my invention will, permit the use of an exhaust nozzle 1 to 1.5 inches wider than obtained in best established practice.

The distance D from the outlet of the stack to the outlet of the preceding intermediate nozzle is what I call the length of the mixing zone of said stack, since the combustion gases entering its intake have a chance to ,mix with the central current while travelling through said distance D. Likewise, E is the mixing zone for the intermediate nozzle. Relative to the outlet diameter,

the length of said mixing zone should be greater.

for the stack than for the intermediate nozzle.

To fully benefit from my invention, the greater part oi the mixing between gas and steam should take place near the throat and within the diverging portion of stack and -intermediate nozzle,

that is, within the distance F and G, respectively.,

For this purpose, I prefer to provide a diverging portion extending over at least 45% of the length of the above deilned mixing zone, but there is usually no reason against adopting a much higher percentage.

Inv accordance with established practice, I give the stack a lesser divergence than cone 20, thereby promoting complete filling by the steam jet and avoiding any down draft from the atmosphere into the smokebox. The stack can also be essentially cylindrical,V but a divergence as specified W'illfunction better in connection with my intermediate nozzle.

The intermediate nozzle, however, according to my discovery, need not be so completely filled by the steam jet, and there is no tendency of a down draft through it, the pressure being the same at intake and outlet. I give the intermediate nozzle a greater divergence than the stack, and preferably a slightly greater or equal divergence than cone 2li. I further make the Vchoke diameter of the intermediate nozzle slightly will tend to rise when the engine is starting on a heavy pull, while with the presently known draft appliances the eilect is just the opposite.

By considerably flaring the intakes i5, i6 of intermediate nozzle and stack, I catch a substantial amount of combustion gases and drive them securely into the steam iet. Moreover, I provide thereby, a gas passage of ample area around the outlet of 'the preceding nozzle and insure that the gases are not being forced into the steam jet before they have been accelerated to high speed by the vacuum drawing them toward the throat. In this wayl I minimize the shock as gas and steam come together, minimizing the resulting losses in energy.

The arrows 2|, 22 indicate the gas flow toward the intake of stack and intermediate nozzle. While I seek to securely guldesaid flow, it is obvious that at some distance from the steam iet, the gas flow will take care of itself. and I found it useless to extend the intake of either stack or intermediate nozzle to the plane of outlet of the preceding nozzle. unless there are other reasons for doing so. However, the distance H, Kbetween two adjacent parts of the draft appliance should not be greater than one third to two thirds of the outlet diameter of the preceding nozzle, meaning that said parts should follow each other in close succession.

Naturally, proportions may be changed from those recommended without departing from the spirit of my invention.

Draft eiilciency may be further increased while retaining all other advantages of my invention by incorporating in the draft appliance more than one intermediate nozzle of the above described characteristics. Fig. 4 shows two of such intermediate nozzles, 9b and 9c. The same principles that have been lexplained in connection with Fig. 3 also apply to Fig. 4, and like reference characters are used for corresponding parts. 'I'he various parts, exhaust nozzle, intermediate nozzles and stack, may be placed closer together than in Fig. 3. The length of the mixing zone relative to the outlet diameter should be about constant for the intermediate nozzles, whereby they become the longer the larger they are in diameter, asshown in the drawings. It is seldom advisable to use more than two or three intermediate nozzles between exhaust nozzle and stack since their effect is impaired in case they are too short.

If the length of the draft appliance, that is the distance A from the exhaust tip to the outlet of the stackiFig. 3) is especially restricted, or if a wide stack is desired, my intermediate nozzle may be adapted to split and spread the exhaust steam. whereof Figures 7, 8, and 9 illustrate a preferred example. In said example, the intermediate nozzle 9d (Fig. 7) is split into four parts near the throat, see Fig. 8 showing a cross section along the line 8 8. The four canals 23 so formed leave passages 24 between themselves through which the combustion gases can enter, as best visible in the top view of said intermediate nozzle, Fig. 9. Split intermediate nozzles are known, but before my invention they have been formed with converging or cylindrical circumferential walls, and therefore with an excessively restricted outlet area which together with the tendency of said circumferentiai walls counterac'ted the'lateral expansion oi' the steam flow instead of promoting it. If,

however, an intermediate nozzle as invented by me is adapted to split the steam, any desirable outlet area may be obtained, a gas passage increasing in cross-sectional area toward the outlet may be provided and the splitting adds to the tendency of my nozzle to spread the steam over a larger area: Thus, a wide stack may be filled with the smallest degree of coercive action on the steam. With this nozzle, the length A of cone 20 may be made only four times the difference between its maximum and minimum diameter, C minus B. although a greater length is recommendable.

It is of course irrelevant for the incorporation of my invention in split intermediate nozzles, whether the splitting is being accomplished by branching the intermediate nozzle as exemplified in Figures 7, 8, and 9, or whether bridges, wedges or other dividing means are placed within the nozzle, leaving the outer walls unbroken. Naturally, also, the canals 23 may be of any number and cross-section. They may, for example, have their edges rounded olf as shown in the top view of a modified intermediate nozzle, Fig. 10, which however I cite only as an example but do not recommend since this construction tends to unnecessarily restrict the outlet area. All this is irrelevant, the criterion being that the outer circumferential walls 25, or what remains of them, are formed according to my invention. But I prefer the form illustrated in Figures 7, 8, and 9 wherein four canals are used, substantially a quarter oi a circle in cross section, also because this disturbs the steam Jet as little as possible and secures most uniform filling of the stack as can readily be understood. I further prefer to contract the gas passages 24 between said canals, toward the center as shown in Fig. 9, whereby excessive spreading of the flow in the center is avoided. which I found very essential.

Split nozzles as hereinbefore described may be used singly as in Fig. 7, or two or more may be superimposed like the plain intermediate nozzles in Fig. 4. Furthermore, one or more split nozzles may be arranged in succession with one or more plain nozzles. Whatever arrangement is to be used depends upon the particular problem to be solved, but what has been said hereinbefore about the practical limitation inthe number of plain intermediate nozzles applies to an even higher degree to split nozzles: In order to avoid intermediate nozzles which are too short relative to their diameter, it is not advisable to combine such split nozzles with more than one additional intermediate nozzle unless there are other reasonsfor doing so, for example, unless a larger number of gas intakes is desired.

It is obvious that my invention is not confined to draft appliances of circular cross section, but that it can be applied to other forms, of which the oblong section shown in Figures 11, 12, and 13 is the most important. The principles explained above in connection with devices of circular cross section can be applied here in an analogous manner and the same reference characters are again used. conforming to analogous parts referred to earlier in this-specification. The significance of the conoidal body 20 and other analogies will be better understood if it is considered that such oblong draft appliance may be regarded as being made up of a number of circular draft appliances of proportions corresponding to the transverse section Fig. 12, all arranged in line and close together, the adjacent walls of which have been removed. But such oblong draft appliances should be made with a slightly lesser divergence than a circular device.

Intermediate nozzles according to my invention may naturally also be used in any combination with hitherto known intermediate nozzles.

Finally, my invention is of course not confined to the conventional form of locomotive having a cylindrical fire tube boiler and a reciprocating steam propelling engine, but it may be incorporated in any steam locomotive wherein exhaust steam is used for creating draft.

I claim:

1. In a locomotive draft appliance, a stack, an exhaust nozzle and one or more intermediate nozzles therebetween, at least one of said interf mediate nozzles having a flaring intake and having circumferential walls diverging toward its outlet, said circumferential walls enclosing a larger cross-sectional area than a hypothetical conoidal body connecting the exhaust nozzle with the top of the stack and having an equal or larger divergence toward their outlet than said conoidal body.

2. In a locomotive draft appliance, a stack, an4

exhaust nozzle and one or more intermediate nozzles therebetween, at least one of said intermediate nozzles having a flaring intake and having circumferential walls /diverging toward its outlet and enclosing a cross-sectional area so much larger than a hypothetical conoidal body connecting the exhaust nozzle with the top of the stack that contact between said walls and the exhaust steam jet is avoided, said circumferential wallsA having further an equal or larger divergence toward their outlet than said conoidal body.

3. In a locomotive draft appliance, a stack, an exhaust nozzle and one or more intermediate nozzles therebetween, at least one of said intermediate nozzles being adapted to split the exhaust steam and having circumferential walls diverging toward its outlet and a flaring intake, the said circumferential walls of said steam-splitting intermediate nozzle enclosing a larger cross-sectional area than a hypothetical coinoidal body connecting the exhaust nozzle with the top of the stack, said circumferential walls having further an equal or larger divergence toward their outlet than said conoidal body.

4. 'I'he combination claimed in claim 3, characterized by the fact that the circumferential walls of the said steam-splitting intermediate nozzle enclose a cross-sectional area so much larger than the said hypothetical conoidal body connecting the exhaust nozzle with the top of the stack, that contact between said walls and the exhaust steam jet is avoided.

5. In a locomotive draft appliance, a stack diverging toward its outlet, an exhaust nozzle and one or more intermediate nozzles therebetween,

at least one of said intermediate nozzles being adapted to split the exhaust steam and having circumferential walls diverging toward its outlet and a fiaring intake, said circumferential walls enclosing a larger cross-sectional area than a hypothetical conoidal body connecting the exhaust nozzle with the top of the stack and having a greater divergence toward their outlet than the stack.

6. In a locomotive draft appliance, a stack, an exhaust nozzle and one or more intermediate nozzles therebetween, at least one of said intermediate nozzles being ,adapted to split the exhaust steam and having a minimum circumference or throat between its inlet and outlet and providing for the gases a cross-sectional area that is larger at said outlet than at said throat, said stack and steam-splitting intermediate nozzle having circumferential walls diverging toward their outlets, the circumferential walls of said intermediate nozzle diverging more than those of the stack.

1. In a locomotive draft appliance, a stack, an exhaust nozzle and oneor more intermediate nozzles therebetween, at least one of said intermediate nozzles being' adapted to split the exhaust steam and having a minimum circumference or throat between its inlet and outlet and providing for the gases a cross-sectional area that is larger at said outlet than at said throat, and having circumferential walls enclosing a crosssectional area s'o much larger than a hypothetical conoidal body connecting the exhaust nozzle with the top of the stack that contact between said walls and the exhaust jet is avoided, lsaid circumferential walls having further an equal or greater divergence toward their outlet than said conoidal body.

8. In a locomotive draft appliance, a stack diverging toward its outlet, an exhaust nozzle and one or more intermediate nozzles therebetween, at least one of said intermediate nozzles being adapted to split the exhaust steam and having a minimum circumference or throat between its inlet and outlet and providing for the gases a cross-sectional area that is larger at said outlet than at said throat, and having circumferential walls enclosing a cross-sectional area so much larger than a hypothetical conoidal body connecting the exhaust nozzle with the top of the stack that contact between said walls and the exhaust jet is avoided, said circumferential walls having further a larger divergence toward their outlet than the stack.

` ADOLF GIESL-GIESLINGEN. 

